What are follicular and Hurthle cell thyroid cancers?

Follicular and Hurthle cell cancers are two different types of cancer, but they are often considered in the same category. Together, these cancers are the second most common thyroid cancer, after papillary cancer. They can occur at any age, but are more likely in older people. These cancers can be hard to diagnose on fine needle aspiration (FNA) biopsy because although the cells look funny or abnormal, there is nothing about the individual cells that are definitive for cancer. In cases of follicular and Hurthle cell lesions, the only way to tell is to look at the capsule surrounding the nodule and see if there is invasion (growth) outside the nodule.

Follicular thyroid cancer does not tend to spread to lymph nodes, but rather spreads through blood vessels to other organs, such as the lungs and bones. Hurthle cell cancers, on the other hand, will sometimes spread to lymph nodes in the neck region, but less commonly than papillary thyroid cancer.

Follicular and Hurthle cell thyroid cancer makes up about 15 to 20% of all cases of thyroid cancer.

These cancers are actually two separate types of cancer, but they are often discussed together because they present and behave similarly. Follicular and Hurthle cell thyroid cancers are somewhat more aggressive than the more common papillary type. Similar to papillary cancer, they are most often discovered as a painless lump in the thyroid. They usually occur after the age of 40 and are more common in women than in men. Although risk factors for follicular and Hurthle cell thyroid cancer include radiation exposure and a family history of thyroid cancer, it is important to note that the majority of patients have no risk factors at all. Fortunately, most patients can be cured if treated appropriately and early enough. Follicular cancer tends to spread through the bloodstream and although it is common, can spread (i.e. metastasize) to the liver, lungs, bones, and brain. Hurthle cell cancers can spread through the blood or to the lymph nodes, but fortunately, metastasis is uncommon.